是否可以上传一个文件.xlsx，处理它而不保存在服务器上?我正在使用jaxrs

Question

我使用jaxrs上传文件*.xlsx。是否可以上传这些文件并在内存中处理它们?我只想读那个文件，用Apache POI处理，并在数据库中保存信息。不保存在服务器

谢谢

Answer 1

很抱歉回复晚了，这个答案可能对某人有所帮助。

是的，可以在内存中读取上传的。xlsx文件的内容[而不将上传的内容保存到物理文件中]。但是这种方法需要更多的内存，因为整个文件内容将存储在缓冲区中。

servlet下面的

是一个工作示例，如果需要，您可以稍微修改一下，将此代码转换为JSP。

在创建XSSFWorkbook对象时传递上传文件的输入流，如下所示，您将能够像示例代码一样读取文件内容。

在WEB-INF/lib文件夹中添加apache-poi jar和apache commons-fileupload.jar，以使此代码正确工作。

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.*;
import org.apache.commons.fileupload.disk.*;
import org.apache.commons.fileupload.servlet.*;
import org.apache.commons.io.FilenameUtils;
import org.apache.poi.openxml4j.opc.OPCPackage;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.util.List;
import java.util.Iterator;
@WebServlet("/FileUploadServlet")
public class FileUploadServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        OPCPackage pkg = null;
        XSSFWorkbook xlsxbook = null;
        InputStream xlsxContentStream = null;
        try {

                boolean isMultipart = ServletFileUpload.isMultipartContent(request);
                if (isMultipart) {
                    List<FileItem> items = new ServletFileUpload(
                            new DiskFileItemFactory()).parseRequest(request);
                    for (FileItem item : items) {
                        if (!item.isFormField()) {
                            String fieldName = item.getFieldName();
                            String fileName = FilenameUtils.getName(item.getName());
                            xlsxContentStream = item.getInputStream();
                            pkg = OPCPackage.open(xlsxContentStream);
                            xlsxbook = new XSSFWorkbook(pkg);
                            XSSFSheet sheet = xlsxbook.getSheetAt(0);
                            Iterator<Row> itr = sheet.iterator();
                            while (itr.hasNext()) {
                                Row row = itr.next();
                                // Iterating over each column of Excel file
                                Iterator<Cell> cellIterator = row.cellIterator();
                                String text = "";
                                double num = 0;
                                while (cellIterator.hasNext()) {
                                    Cell cell = cellIterator.next();
                                    switch (cell.getCellType()) {
                                    case Cell.CELL_TYPE_STRING:
                                        text = cell.getStringCellValue();
                                        break;
                                    case Cell.CELL_TYPE_NUMERIC:
                                        num = cell.getNumericCellValue();
                                        break;
                                    default:
                                    }
                                }
                                out.print(text + " " + num);
                                //call database insert method here and pass the xlsx column values
                            }
                        }
                    }
                }
                out.flush();
            } catch (FileUploadException e) {
                throw new ServletException("Cannot parse multipart request.", e);
            } catch (Exception e) {
                throw new ServletException("", e);
            } finally {
                if(null!=xlsxContentStream){ xlsxContentStream.close();}
                if(null!=pkg){ pkg.close();}
            }
        }

protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }
}

你的jsp/html文件应该有enctype="multipart/form-data"

<form action="FileUploadServlet" name="form2" method="post" enctype="multipart/form-data">
Select a .xlsx File to upload :<input type="file" name="file" id="file" size="50" /> 
<input type="submit" value="Upload xlsx File"/>
</form>